One-off small scale cutting/machining recommendations

[Danny B]

I need someone who can help me cut the parts for a featherweight drum spinner, namely a pair of 120mm wide, 12mm thick toothed Hardox 500 discs (rough sketch below) and a chunky aluminium pipe to join them. Since balance is everything, it would be silly to do this manually.
But I've been ringing around various companies in the West Yorkshire area, and they all seem to either be completely uninterested or would impose a hefty service charge that far outstrips the price of the material (best I could get for waterjet cutting was £120 JUST IN SETUP, EXCLUDING CUTTING COST just to do £40 worth of Hardox, which really doesn't seem worth it).

If anyone knows a company/person that can help, I'd really appreciate it because my budget doesn't stretch a terribly long way.

Thanks,

Danny

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[Pinski1]

Usual rule of thumb is minimum hole diameter is equal to material thickness. Those tiny holes around the perimeter may be the cause of your inflated quotes. I've used K-Cut in the past, as have many others, found them to be good.

[R9000]

Yeah, email Kcut. They'll get you sorted out.

[Danny B]

What sort of prices have you managed to get from them in the past?

[R9000]

My order of Hardox parts for my featherweight (some 4mm, some 6mm, some 10mm) was around £110 all said and done, material included. Don't underestimate the price of Hardox (or any decent steel I guess) but their cutting services are very reasonable, and the delivery is usually next-day from my experience. Compared to quotes I've had from other places, they're head-and-shoulders above with value for money.

[Danny B]

Excellent, I've just sent them an enquiry email. As a matter of interest, what grades of Hardox do they supply? I've found some 500 on Ebay, but I'd prefer 550 or 600 if possible.

[R9000]

I'm honestly not sure, you'll have to ask what they have in stock at what thicknesses. My parts were Hardox 500 though, and that stuff is tough. Oh! And something to bare in mind, from my experience they always cut holes slightly smaller than they should be. Not that it should be a problem for balancing parts or weight saving, but for example, I've specified M5 and M10 holes and had to drill them out to be able to fit the bolt through. I've never spoken to them about this, but maybe you want to specify a little larger if you don't want to do any extra drilling or grinding. Just be careful I suppose.

[Ellis]

It's definitely good practice to oversize holes in water, laser and particularly plasma-cutting. For K-Cut (water), I find 0.5mm over about right on average (for minimal cleanup) or around 0.8mm over if you want 0 hassle. Of course, this lowers the overall accuracy of your assembly so shooting lower and expanding the holes exactly might be desirable. Dremel tool with a carbide burr works nicely!

[R9000]

My first kcut order included the brackets that support my FW's lifter, but also fit over the drill motors. Took quite a while of grinding the 30-ish mm holes out with my little rotary tool before I could finally fit them over the motor cans. Plus, expanding a hole with a drill that's almost the size you want (but not quite) is the worst, I find. The tip has nothing to bite into and you end up putting all the pressure on the outside edges of the bit. A real pain if it's Hardox like this. I'll have to try a burr next time.

[typhoon_driver]

Of course, the other way to go is to include tolerances on your drawings. Any manufacturing company worth it's salt should be able to hit reasonable tolerances for parts. Make sure to make them aware of the tolerances.